An endoscope is a probe which generally consists of a flexible or rigid tube that allows viewing of the inside of the body. A physician or medical specialist inserts one end of the endoscope (distal end) through a natural orifice such as the anus or mouth into a natural cavity such as the gastrointestinal tract. The endoscope contains a mechanism for conducting light from a light source external to the body to illuminate the internal cavity. The end of the endoscope which is not inserted (proximal end) is connected to a source of light which is coupled to the light conducting mechanism by optical components such as lenses or mirrors. The endoscope further contains a second mechanism for conducting light from the inside of the internal cavity to a viewing mechanism. The viewing mechanism may consist of an optical device which may be directly coupled to the eye of the medical specialist, or it may be coupled to a camera such as a video camera for viewing on a video monitor. An endoscope thus allows a medical specialist to see the inside of the cavity and to diagnose disease, anomalies, and the like. However, it does not provide any mechanism for applying therapy.
Endoscopes have also been developed with an ultrasonic device built at the distal end, and coupled with appropriate electronics at the proximal end, to perform ultrasonic imaging of the surfaces underlying the wall of the cavity. A probe having both optical viewing and ultrasonic imaging capabilities is described in U.S. Pat. No. 4,327,738 to Green et al. (1982). These devices provide another way to evaluate the health state of the tissue or organs, yet they still do not allow applying therapy.
Similarly, laparoscopic probes are a variation on the concept of endoscopes. Laparoscopic probes are inserted into the body through a perforation made into the skin, to observe and manipulate internal tissue and organs. Laparoscopic probes also require visual guidance, using optical visualization systems similar to those used in endoscopes, although sometimes the illumination, vision and manipulation probes are separate and inserted through separate skin incisions. Some laparoscopic instruments have been developed that contain ultrasonic imaging devices built into the distal end, for imaging beneath the surface of the organs that are visible by an optical viewing mechanism. Because of the expanded access to the organ in question via ad-hoc perforations, laparoscopic devices are very suited for surgery of internal organs by the use of miniature scalpels that are controlled or manipulated from a position external to the body.
While the images obtained by illumination or ultrasound in the prior art endoscopes and laparoscopes have proved to be a valuable tool in medical diagnosis, they do not directly perform the treatment of the identified anomalies.
Recently, ultrasound technology has been developed for use in providing therapy. Therapeutic ultrasound relies on applying ultrasonic waves of such intensity that tissue is heated to very high temperatures by the waves. When the tissue is heated to 42-45 degrees centigrade for extended periods of time, some physiological changes in the cells occur. This form of therapy is called hyperthermia. When tissues are heated to 60 degrees or higher, some cells are destroyed. This form of therapy is called ablation. The technology that performs this ablation requires high intensity ultrasound obtained by sharply focusing the acoustic waves. This form of ultrasound is generally known as "high intensity focused ultrasound", or HIFU.
The use of HIFU to treat anomalies has been mainly used extracorporeally (i.e. from outside the body). However, some organs and tissue to be treated may be inaccessible to extracorporeal beams due to obstruction by bone, lung or other major organs that do not allow the passage of ultrasonic waves.